The dispute concerns an agreement that eBay made when it bought Skype in 2005. The acquisition did not include Skype's peer-to-peer networking technology, which is owned by Joltid and was licensed to Skype.

Earlier this year Joltid terminated the licence agreement. Joltid and Skype have since argued over the validity of the termination in courts in England. Further arguments are scheduled there in the middle of next year.

"Joltid terminated its licence agreement with Skype as a result of breaches by Skype. Skype has infringed Joltid's copyrights," Joltid said in a statement. "Joltid will vigorously enforce its copyrights and other intellectual property rights in all of the technologies it has innovated."

In the meantime, eBay has said it's developing an alternative technology to get around the licensing issue.

The US lawsuit seeks an injunction against Skype and statutory damages for copyright infringement. Representatives for eBay and Skype did not respond to requests for comment.

Earlier this month, eBay agreed to sell a 65 percent stake in Skype for $1.9bn to a group of investors led by Silver Lake. The deal, expected to close in the fourth quarter, values Skype at $2.75bn, just over the $2.6bn that eBay paid for it in 2005.